How to use pulseIn in arduino

[zxlzy]

I want to use this https://www.arduino.cc/reference/en/language/functions/advanced-io/pulsein/

[Rahix]

Right now, there doesn't exist any plug-and-play replacement - you'll have to build your own. Depending on what you need, you can repurpose some of the code from the HC-SR04 example. This part in particular uses a timer to measure the response time of he sensor:

avr-hal/examples/arduino-uno/src/bin/uno-hc-sr04.rs

Lines 36 to 69 in c9b9268

	// the timer is reinitialized with value 0.
	timer1.tcnt1.write(|w| unsafe { w.bits(0) });
	// the trigger must be set to high under 10 µs as per the HC-SR04 datasheet
	trig.set_high();
	arduino_hal::delay_us(10);
	trig.set_low();
	while echo.is_low() {
	// exiting the loop if the timer has reached 200 ms.
	// 0.2s/4µs = 50000
	if timer1.tcnt1.read().bits() >= 50000 {
	// jump to the beginning of the outer loop if no obstacle is detected
	ufmt::uwriteln!(
	&mut serial,
	"Nothing was detected and jump to outer loop.\r"
	)
	.void_unwrap();
	continue 'outer;
	}
	}
	// Restarting the timer
	timer1.tcnt1.write(|w| unsafe { w.bits(0) });
	// Wait for the echo to get low again
	while echo.is_high() {}
	// 1 count == 4 µs, so the value is multiplied by 4.
	// 1/58 ≈ (34000 cm/s) * 1µs / 2
	// when no object is detected, instead of keeping the echo pin completely low,
	// some HC-SR04 labeled sensor holds the echo pin in high state for very long time,
	// thus overflowing the u16 value when multiplying the timer1 value with 4.
	// overflow during runtime causes panic! so it must be handled
	let temp_timer = timer1.tcnt1.read().bits().saturating_mul(4);